Apparatus for making cellular products



Jan. 21, 1964 J. w. wHrrE 3,118,958

APPARATUS FOR MAKING CELLULAR PRODUCTS Original Filed May 6. 1957 GASi/Lw i. 108 l i6 DISCHAQGE lllllli 11o INVENToR.

United States Patent 3,118,958 APPARATUS FR MAKING CELLULAR PRODUCTSJohn W. White, North Hollywood, Calif., assignor to Mildred M. Kelly,Los Angeles, Calif. Continuation of application Ser. No. 657,370, May 6,1957. This application Feb. 10, 1960, Ser. No. 10,531 6 Claims. (Cl.261-87) This invention relates 'generally to .apparatus -for makingcellular products, and more particularly relates to apparatus .forcontinuously aenating or foaming of liquids such as rubber latexdispersions.

`In the production of foam rubber, it has been the practice to foam therubber latex dispersion by beating or wlhipping air into it, or in someinstances, to inject air into the liquid by means of a plurality ofhypoderrnic needles. FFliese methods are reasonably satisfactory inbatch operations, but are not practical in a continuous process.

It has also been proposed to provide, in apparatus adapted forcontinuous foam rubber processing, a means for injecting gas into therubber latex in extremely minute and uniform manner which comprises thepassage of gas under pressure through a microporous plate or wall havingextremely small pores, of the order of microns, as the rubber latexpasses in intimate contact over the porous plate. In this manner, afiner and more homogenous cell structure produced in the foam rubberproduct. While the apparatus just described is highly advantageous andsuperior to the other methods yfor continuously foaming latex, someditliculty has been experienced because of the build-up of latex, aftersome hours of operation, on the porous plate, thereby preventing thedischarge of gas into the passing latex. In such cases, the machine mustbe ydisassembled and cleaned-or a new plate or wall employed. In anyevent, a loss of production results while the machine is beingdisassembled'.

Bearing in mind the foregoing facts, it is a major object of the presentinvention to provide an impro-ved apparatus for the 'continuousproduction of cellular products, particularly foam rubber and othercellular rubber products.

Bearing in mind the foregoing facts, it is a major 0bject of the presentinvention to provide an improved apparatus for the continuous productionof cellular products, particularly foam rubber and other cellular rubberproducts.

Another object of the present invention is to provide improved apparatusfor the continuous production of cellular pro-ducts which incorponates amicro-porous plate through which a gas is passed in uniform and fineamounts into the material to be foamed, and in which build-up of thematerial on the porous plate is minimized.

It is a further object of the present invention to provide apparatus ofthe character described which reduces the amount of material build-up ona porous plate to a minimum by equ-alizing the pressure in the materialas the material volume expands due to foaming, while still maintainingthe material in intimate contact with the porous plate as it is foamed.

Still yanother object of the present invention is to provide anapparatus of the character described wherein liquid material may beintroduced, mixed and aerated within an extremely small volume, and lona continuous basis.

It is also an lobject of the present invention to provide apparatus ofthe character described wherein an improved means for ready disassemblyof the apparatus during cleaning is provided, thereby minimizing loss ofproduction time.

The stated and other objects and advantages of this invention will beapparent from the following description of a preferred form thereof, andfrom the accompanying drawings, in which:

FIGURE 1 is a vertical longitudinal section of the mixing and foamingapparatus;

FIGURE 2 is a sectional view taken along the line 2 2 of FIGURE 1; and

FIGURE 3 is a sectional View taken along the line 3-3 of FIGURE 1.

Referring now generally to the drawings, the apparatus of my linventionis designated by the numeral `10 and comprises, at the left end thereof,a mixing section .12, a foaming section 14 in the lcentral portionthereof, and a discharge section -16 at the right end thereof. Theliquid to be lfoamed, for example, a latex dispersion, enters the mixingsection 12 .and passes through a mixing chamber 18 contained therein.The liquid then enters a narrow, conical, progressively enlargingpassageway 20 provided in the foaming chamber or section 1'4. A gas,such as air, is injected into the passageway v20 through each of theporous Walls defining rthe passageway 20, thu-s uniformly aerating thematerial. The aerated material is then discharged into a dischargechamber 22 for-med within the discharge section 16 and leaves theapparatus 10 to be sent to molds for curing, or to other process steps,`depending upon the particular liquid involved.

Referring now specifically `to :FIGURE l, the mixing section 12 isremovably connected to the foaming section 1'4 by -any suitable means,such as by the wing nut and bolt construction 26. The mixing chamber 18is provided with an inlet passage 30.

In foam rubber production, the latex feed comprises a variety ofingnedients, such as -a stabilizer, gelling agent, plasticizer and thelike, some of which are added just prior to the foaming operation. Aspecific process for which my apparatus is particularly well suited isdescribed and claimed in Patent No. 2,885,372 issued May 5, 1959 toIch'n Hu'gh Kelly, Jr. In this process, a plurality of `dissimilar latexdispersions, one of which contains the gelling agent, are interm-ixedjust prior to the foaming operation, the mixing operation beingadvantageously lconducted in the mixing chamber .'18 to be nowdescribed.

The mixing chamber 18` is generally cylindrical in shape and is providedwith a rotary shaft 32 extending axially therethrough, one end of whichis aixed to a second axially aligned shaft 38, in any suitable manner,as by a screw connection 40. 'Ille opposite end 42 of the shaft 32 ismounted in a bearing within the housing 44- of the mixing chamber y18.The shaft 32 has affixed thereto a plural-ity of radially extending rodsor padding 45 which are `spaced about its periphery and extend over thelength of the shaft.

The right end 46 of the shaft 38 is adapted to be connected to a sourceof power (not shown). The shaft 32 is thus rotatable with the rotationof the shaft 38, thereby enabling the mixing paddles 45 to thoroughlymix liquid material entering the chamber 18. The mixing is further aided'by the provision of turbulence-creating rods 47 mounted across inletpassage 30.

`Measured amounts of liquids are Ifed to line 30 under substantialpressure so that they will readily travel through the mixing chamber 18and into the foaming section 14. The liquid, after being thoroughlymixed in the chamber 18, as above described, passes from the outlet end48 thereof and into the narrow annular mouth or inlet 50 of each memberbeing made of a porous material having a mean pore diameter of the orderof from 5 to 65 microns. The -raw material preferably used is stainlesssteel powder of uniform particle size heat-treated to form a strongsheet of any desired shape.

The outer female porous conical member 54 is affixed to the housing 56of the foaming section 14 by any appropriate means. For example, thelarger open end 58 of the member 54 is provided with an outwardlydirected annular ange 60 which is connected to the housing 56 by meansof a plurality of screws 62. The smaller circular open end 64 of theconical member 54 is press fitted within a complementary side opening 66in the housing 56, and defines the outer surface of the mouth 50 of thepassageway 20.

The male conical member 52, which defines the inner wall of the passage20, is formed with an open smaller end 67 which is slidably fitted ontothe rotatable shaft 38. The member 52 is adapted to rotate with theshaft 38 by means of a mounting sleeve 70 as follows: the mountingsleeve 70 is first mounted on the shaft 38 by means of an adjustingfiat-head screw 76, the mounting sleeve being in turn affixed to thelarger end 72, of the conical member S2 by screw connections 77.

As the liquid to be foamed enters the conical passage 20 from the mixingchamber 18, the liquid is restricted between the walls 52, 54 of thepassage so as to be in intimate contact therewith. A multiplicity ofmicroscopic gaseous blasts is then forced into the passing liquidthrough both porous walls 52 and 54 to thoroughly and uniformly foam theliquid.

The gas, forced through the female porous conic section 54, is injectedfrom a gas chamber 80, the walls of which are defined by the housing S6of the foaming section 14 and the porous wall 54 itself, the chamber 80being fed by gas entering a gas inlet conduit 82 under pressure.

The gas, forced through the male porous conic section 52, is injectedfrom a second gas chamber 86, the walls of which are defined by theinner surface of the conic section 52, the inner surface of the mountingsleeve 70, and the outer surface of the shaft 38. The gas chamber 86 isfed by gas entering a gas inlet conduit 88 mounted Within dischargechamber 22, the gas passing from the conduit 88 through a passage `90fonmed in the shaft bearing member 94, thence through an annular groove96, formed on the periphery of the rotary shaft 38, and transverselyaligned with the passage 90, to an elongated gas passage 98 formedwithin the rotatable shaft 38. (It will be noted that the gas passage 98is closed at its left end by the threaded end 40 of shaft 32.) The gasthen passes from the elongated gas passage 28 into the chamber 86through a transverse port 100. The gas entering inlet conduit 88 ispreferably maintained at approximately the same pressure as the gasentering inlet 82.

It will be seen that gas entering the conduit 88 will enter theelongated gas passage 98 regardless of the angular position of therotary shaft 38, inasmuch as the annular groove 96 is in constantcommunication with the conduit 88 regardless of the relative angularposition of the shaft 38. Also it will be seen that the port 100 isalways in communication with the chamber 86 regardless of the angularposition of the rotatable shaft 38 with respect thereto. In this manner,the rotary porous member 52 will always have a continuous supply of gasbeing forced therethrough.

The porous member 52 is made rotatable in order to insure uniformdispersion of the multiplicity of minute air jets or streams issuinginto the passage 20 during movement of material therethrough. Therelative rotation of the conical members 52, 54 facilitates movement ofthe liquid toward the discharge section 16 and tends to equalize theflow across all parts of the conical passage 20. The speed of relativerotation of the conical members 52, 54 ranges preferably between 100 and400 r.p.m.

The presence of two gas chambers 80, 86 is sufficient,

in some instances, to distribute, and force, the gas through the entiresurface of the porous walls 52, 54 to obtain a uniform foaming of theliquid passing through the passage 20 without the need for relativerotation of the porous walls, as just described. It will be noted that abearing seal 102 is provided at the juncture of the mixing and foamingsections 12 and 14 to minimize leakage of gas from the apparatus 10.

The problem faced by the prior art of the build-up of material upon thewalls of the foaming passage, particularly when foaming rubber baseliquids, is, to a large extent, overcome by the use of the pair ofconical porous members of the type described. As the latex passesthrough the foaming passage, the foaming thereof considerably increasesits volume. If the passage is designed so as to be progressivelyenlarged in proportion to the increase in volume of the liquid due tothe foaming, the pressure upon the porous walls of the passage becomessubstantially equalized and build-up of the liquid upon the porouspassage walls, with consequent clogging of pores of the walls, isprevented or substantially reduced.

It will be seen that, by providing a progressively widening passageway20, the volume increase of the passage 20 from its inlet end 56 to itsoutlet end 104 can be made to increase in proportion to the increase involume of the liquid passing therethrough due to the foaming. Forexample, if the volume increase due to foaming is eightfold from inlet50 to outlet 104, increase in volume of the passage from the inlet tothe outlet would be also made eightfold.

The exact amount of volume increase desired in the passage 20 isobtained by choosing the conic section having the proper taper andlength. The taper of each conical section 52, 54 is generally the same,but can be dissimilar when desired. If the width of the conical passage20 does increase in the passage is thereby provided.

Adjustment means for the passage width is required so that exact passagewidths may be provided whereby the liquid mixture is forced to flow inintimate contact with the adjacent faces of porous walls 54 and 52,while it is subjected to a multiplicity of air streams emergingtherefrom. To this end, the fiat-head screws 76 mounted in the mountingsleeve 70 are adapted to engage an elongated, flat-bottomed groove ordepression 106 formed within the periphery of the shaft 38. Uponloosening the adjusting screw 76, the mounting sleeve 70 and the maleconic member 52 are movable in the direction desired to form anappropriately sized passage 20. The conic member 52 is then stablypositioned by tightening screw 76 until it abuts the bottom of thegroove 106.

After complete foaming of the liquid, as described, the foamed liquid isdischarged from the outlet end 104 of the passage 20 into the dischargechamber 22 of discharge section 16. The discharge section 16 is mountedto the foaming section 14 by any suitable means allowing quickdisassembly, such as by a wing nut and bolt construction 108. The shaft38 extends through the discharge section 16 and is rotatably mountedwithin the bearing 94, the right end 46 of the shaft being adapted to beconnected to a source of power, as previously mentioned. The dischargesection 16 is affixed to a suitable fixed base (not shown).

Inasmuch as the size of the gas bubbles in the foamed material dependsto some extent upon the back pressure in the foaming chamber 14, thedischarge chamber is preferably provided with a variable area discharge,as, for example, by the use of a discharge plate (not shown) coveringthe discharge end (not shown) and having a variable opening formedtherein.

The foamed liquid then passes from the discharge chamber 22 and isusually sent to molds for curing, or to other process steps, dependingupon the particular liquid involved.

In the operation of the apparatus in the continuous production of foamrubber, measured amounts of latices are continuously introduced into theinlet passage 3f). The latices are thoroughly intermixed by the rotationof paddles 45. The mixture then passes into the inlet end 5f) of theconical passage 20 and is spread over the entire surface of the passagewalls 52, 54, aided by the rotation of the conical member 52. As themixture passes through the conical passage 2f), it is thoroughly foamedby a multiplicity of extremely fine air blasts issuing from both sidesof the passage 20 through the porous walls 52, 541. The extent ofbuild-up on the porous walls of llatex is minimized by provision of aprogressively increasing volurne per unit length of passage 20, thepassage volume increasing in proportion to the rate of increase involume of the latex as it moves through the passage 20.

In accordance With the process of said Patent No. 2,885,372 issued toJohn Hugh Kelly, I r., one of the latices will have therein a gellingagent adapted to initiate gelling of the other latex and the timing ofthe apparatus will therefore be such that complete intermixing andfoaming are had and the mixture discharged from the apparatus 10, beforenoticeable gelling takes place. It Will be readily appreciated that bythe apparatus herein shown, all the variables of the process can bereadily and accurately controlled without complex auxiliary equipment.

The apparatus has been designed for rapid disassembly whereby access tothe vital parts of the apparatus is quickly provided. For this purpose,the housing 56 of the foaming section 14 is adapted to slide on a railbase 110. In disassembling the apparatus 1t), the Wing nuts 26 and 108which afx the mixing section 12 and the discharge section 16 to thefoaming section 14, respectively, are first removed. The housing 44 ofthe mixing section 12 is then taken away, and the mixing paddles 45 areremoved by merely unscrewing the threaded end 40 of the shaft 32 fromthe shaft 38.

The foaming section 14, during operation of the appara-` tus 10, isclamped to the rail base 11i) by clamping means 112 which consists, forexample, of a clamping plate 114 adapted to be loosened and tightened bya knurled nut 116 to thereby lock and unlock the foaming section ontothe rail base. After unlocking the clamping means 112, the foamingsection 14 is then slidably moved to the left away from the dischargesection 16, thus completely separating the two conical sections 54, 52so that each may be completely cleaned or replaced, as desired. Whilehousings of the various sections are separated, adjustment of theconical passage 2t) can be made by axial movement of the conic member52, as described previously.

In assembling the apparatus, the paddles 45 are attached to the shaft 32and the sections 12, 115i and 16 affixed to each other. The clampingmeans 112 is then tightened to lock foaming section 1li in place, andthe apparatus is ready for operation. The Various air inlet and liquidinlet lines are, of course, fiexible to accommodate the movement of themixing and foaming sections 12, 14 during assembly and disassembly.

This patent application is a continuation of my copending patentapplication Serial No. 657,370 filed May 6, 1957 for Apparatus forMaking Cellular Products, and now abandoned.

While the apparatus herein shown and described has been describedparticularly with respect to several embodiments, it will be apparentthat substantial changes and modifications can be made within the spiritof the invention. Therefore, I do not intend to be limited by theembodiment herein shown and described, but only by the appended claims.

I claim:

1. Apparatus for foaming materials which comprises:

a housing;

a shaft rotatably mounted within said housing;

means to rotate said shaft;

a first hollow, porous conic section coaxially mounted onto saidrotatable shaft, the inner surface of said first conic section and thewall of said rotatable shaft defining a first gas chamber;

a second hollow, porous conic section affixed to said housing, saidfirst conic section being coaxially disposed within said second conicsection, said second conic section surrounding said first conic sectionin closely spaced relationship therewith, and said first and secondconic sections having their projected apexes located at the same end toform a continually diverging conic passageway therebetween, said secondconic section and said housnig defining a second gas chamber;

means for supplying gas under pressure into said gas chambers, wherebysaid gas is forced through said porous conic sections into said conicpassageway in the form of a multiplicity of gaseous blasts;

and means for conducting foamable material into and through said conicpassageway whereby said material is subjected to said gaseous blasts tothereby uniformly and completely foam said material.

2. Apparatus according to claim l wherein means are provided forslidably moving said housing and said second conic section away fromsaid first conic section to facilitate cleaning.

3. Apparatus of the character described which includes:

a mixing chamber having an outlet end and an inlet end;

a foaming chamber adjacent said mixing chamber having an inlet and anoutlet end, said inlet end of said foaming chamber communicatingdirectly with the outlet end of said mixing chamber;

a shaft extending through both said mixing chamber and said foamingchamber;

liquid agitating means affixed to a portion of the shaft within saidmixing chamber;

means to rotatably mount said shaft within said chambers;

means to rotate said shaft;

a first porous, conic wall mounted on said shaft, in

said foaming chamber, to rotate therewith;

a second porous, conic wall surrounding said first conic Wall in closelyspaced relationship therewith, said first conic wall being coaxiallydisposed within said second conic wall, and said first and second conicwalls having their projected apexes located at the same end to form aconic passage continually diverging from said inlet end of said foamingchamber to said outlet end of said foaming chamber;

means for directing gas under pressure through both of said porous conicwalls and into said conic passage;

and means for conducting foamable material from said mixing chamber tosaid conic passage whereby said material is subjected to a multiplicityof minute gaseous blasts to foam the same upon movement of the materialthereacross.

4. Apparatus according to claim 3 characterized in that a portion ofsaid rotatable shaft upon which said agitation means is aflixed hasmeans to threadably connect said portion to the remaining portion ofsaid rotatable shaft for ready removability of said agitation means.

5. Apparatus of the character described which includes:

means defining a mixing chamber and an adjacent foaming chamber;

passage means connecting said chambers;

a shaft extending from said mixing chamber, through said passage means,and into said foaming chamber;

means to rotatably mount said shaft;

means to rotate said rotatably mounted shaft;

radial beater elements mounted on that portion of said shaft lyingwithin said mixing chamber;

a rst porous, conic section, having an inner surface and an outersurface, coaxially mounted onto said shaft in said foaming chamber;

means for adjusting the location of said first conic section on saidshaft;

a second porous conic section affixed within said foaming chamber, saidfirst conic section being coaxially disposed within said second conicsection, said second conic section surrounding said first conic sectionin closely spaced relationship therewith and said first and second conicsections having their projected apexes located at the same end to form acontinuously diverging conical passageway, in said foaming chamber,having its smaller inlet end in direct communication with said passagemeans;

means for directing gas under pressure through each of said conicsections and into said conical passageway in the form of a multiplicityof fine air jets;

means for supplying controlled amounts of foamable material to saidmixing chamber under pressure stiflicient to cause them to flow intosaid foaming chamber and into said conical passageway whereby as saidmaterial flows through said conical passageway it is foamed by said airblasts;

and means forming a chamber for receiving said foamed material, saidchamber having a discharge port.

6. Apparatus for foaming material which includes:

a mixing chamber having an inlet and an outlet for receiving anddischarging foamable material;

a housing defining a foaming chamber having an inlet and an outlet, theinlet of said foaming chamber being in communication with the outlet ofsaid mixing chamber;

a shaft passing through both of said chambers and provided with meansfor agitating the material in said mixing chamber;

means for rotatably mounting said shaft;

means for rotating said rotatably mounted shaft;

a first conic section composed of porous material,

the mean pore diameter of said porous material lying between 5-65microns, said first conic section being affixed to said shaft, withinsaid foaming chamber, for rotation with said shaft;

a second porous conic section mounted on said housing, said second conicsection surrounding said first conic section in closely spacedrelationship therewith, said first conic section being coaxiallydisposed within said second conic section, and said first and secondconic sections having their projected apexes located at the same end toform a continuously diverging conical passageway having its smallerinlet end in communication with said outlet of said mixing chamber;

a first gas receiving chamber defined by said first conic section andsaid shaft in said foaming chamber;

a second gas receiving chamber defined by said second conic section andsaid housing;

means for directing gas, through each of said gas receiving chambers,under pressure, said gas passing from said gas receiving chambersthrough said porous conic sections and into said conical passageway as amultiplicity of fine air streams;

means for supplying controlled amounts of foamable material to saidmixing chamber under a pressure suiicicnt to cause them to flow fromsaid mixing chamber into said foaming chamber and through said conicalpassageway, said multiplicity of gas streams uniformly foaming saidmaterial as it flows through said conic passageway;

and means for slidably moving said housing and said second conic sectionof said foaming chamber away from said first conic section to facilitatecleaning.

References Cited in the file of this patent UNITED STATES PATENTSGoebels Aug. 28, 1934 McAllister July 3, 1951 Alderfer Nov. 10, 1953Kelly et al. May 7, 1957 Williams Mar. 4, 1958 FOREIGN PATENTS GreatBritain July `29, 1953

1. APPARATUS FOR FOAMING MATERIALS WHICH COMPRISES: A HOUSING: A SHAFTROTATABLY MOUNTED WITHIN SAID HOUSING; MEANS TO ROTATE SID SHAFT; AFIRST HOLLOW POROUS CONIC SECTION COAXIALLY MOUNTED ONTO SAID ROTATABLESHAFT, THE LINNER SURFACE OF SAID FIRST CONIC SECTION AND THE WALL OFSAID ROTATABLE SHAFT DEFINING A FIRST GAS CHAMBER; A SECOND HOLLOW,POROUS CONIC SECTION AFFIXED TO SAID HOUSING, SAID FIRST CONIC SECTIONBEING COAXIALLY DISPOSED WITHIN SID SECOND CONIC SECTION, SAID SECONDCONIC SECTIO SURROUNDING SAID FIRST CONIC SECTION IN CLOSELY SPACEDRELATIONSHIP THEREWITH, AND SAID FIRST AND SECOND CONIC SECTIONS HAVINGTHEIR PROJECTED APEXES LOCATED AT THE SAME END TO FORM A CONTINUALLYDIVERGING CONIC PASSAGEWAY THEREBETWEEN, SAID SECOND CONIC SECTION ANDSAID HOUSING DEFINING A SECOND GAS CHAMBER; MEANS FOR SUPPLYING GASUNDER PRESSURE INTO SAID GAS CHAMBERS, WHEREBY SAID GAS IS FORCEDTHROUGH SAID POROUS CONIC SECTIONS INTO SAID CONIC PASSAGEWAY IN THEFORM OF A MULTIPLICITY OF GASEOUS BLASTS; AND MEANS FOR CONDUCTINGFOAMABLE MATERIAL INTO AND THROUGH SAID CONIC PASSAGEWAY WHEREBY SAIDMATERIAL IS SUBJECTED TO SAID GASEOUS BLASTS TO THEREBY UNIFORMLY ANDCOMPLETELY FOAM SAID MATERIAL.